I am about half way through his book, so I am not sure of his experience, but I can tell you mine.
It's not that you get worse over time, but you come up with methods of handling certain situations. And none of them are logical to an outsider. So what might be viewed as worse is actually a method of coping than enables "better" results.
For example, Howie cannot shake hands, but he can do a fist bump.
The problem is that it is almost impossible to get past the thoughts. For example, I have a panic attack every day when I go to work that I am going to need to use the bathroom and I am not going to make it. This happens to me every day, and I know it is completely illogical, but once I have the first thought of needing a bathroom, I cannot stop thinking about it. When I get to work, I do not even have to go, but now I know where one is when I need it. For example, the first thing I do when I go anywhere is find a bathroom. Not to go, but just to know where it is. And until I do, I cannot stop thinking about it.
So how do I cope, I only go to places that I know, so that I can minimize my panic attacks. It seems worse from the outside, but it is better on the inside.
It is not logical, so it is hard to explain.